Torpedo director



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g ,L 1o slghthne Y i l cul/:onen of owgrca; l I edlto ||\e corr 55a sa 6 905mm /06 sineof torpedo L 80 f ein 54\ 69 7/ 73 74 59` LE" Tonvzno consum mss ce SPEED eed 84 87 "aree o s D molcnon 76 ropporinm' l dlspluclenli oran e DIDDOI Dnc 70 7/q 75 s mmm 6*/ 72 com neni of posmonm omteo 1o sight line /20 77 RToIOAl-:Tfggillull l/J i GSOPNESETDANT /l` INVENTOR CHARLES BOUT/N ATTORNEY Patented Aug. 3, 1954 UNITED STATES PATENT OFFICE (Granted under Title 35, U. S. Code (1952),

sec. 266) 2 Claims.

This invention relates to ordnance fire control and more particularly to a novel method and apparatus for use in directing a torpedo from a moving craft to a target. The present invention is characterized by its use, in a new manner, of the .principle that when a torpedo is released on a sight line to a target and on a bearing having a torpedo velocity component perpendicular to the sight line and equal to and in the same direction as the target velocity component perpendicular to the sight line, with the torpedo and target having a net component of velocity toward each other, the torpedo will effect a collision with the target.

For illustrative purposes, the invention will be described in connection with a method and apparatus for directing a torpedo from an air-craft to a target, although it will be understood that the invention may be used on other types of crafts, such as surface and subsurface craft.

One object of the present invention resides in the provision of a method and apparatus for use in directing a torpedo from a moving craft to a target, in which the torpedo bearing and torpedo release point necessary to effect a torpedo hit on the target are computed quickly and accurately.

Another object of the invention is to provide a method and apparatus of the character described which is particularly adapted for use on an aircraft against a moving target.

Still another object is to provide a method and apparatus of the character described which permit a wide latitude for maneuvering of the attacking craft after computation of the necessary torpedo bearing and release point and prior to release of the torpedo, whereby the attacking craft is less vulnerable to counter-action from the target.

An additional object is to provide an apparatus of the character described in which the computations require only a few manual operations.

A further object is to provide an apparatus of the character described which may be made in a compact form of relatively simple construction.

Still another object is to provide a method and apparatus of the character described in which a sight line is established from the attacking craft to the target, preferably by a directionally stabilized sight, and the sight is adjusted in train, partly automatically and partly manually, to maintain the target in the vertical center of the sight during the attacking run, whereby the torpedo bearing and torpedo release point necessary to hit the target are automatically computed.

In accordance with the invention, an original sight line is established to the target, preferably by training upon the target a directionally stabilized sight. The velocity component of the attacking craft perpendicular to this sight line is continuously computed, and from this velocity component a correction factor is subtracted representing the velocity component of the target perpendicular to the sight line. The remainder of these two components is multiplied by time to provide a continuous indication of the displacement of the attacking craft from a sight line through the target and parallel to the original sight line. The sight is rotated in train through an angle whose sine is a function of this displacement, the above noted correction factor being adjusted manually to maintain the target image against azimuth displacement in the sight. This adjusted correction factor is utilized in computing the torpedo bearing necessary to provide a torpedo velocity component perpendicular to the sight line and equal to and in the same direction as the target velocity component represented by the correction factor when the target image is maintained in the vertical center of the sight. Thus, when the torpedo is released on the computed torpedo bearing to cause the torpedo to enter the water at Zero displacement as represented by the displacement indication, the torpedo will effect a collision with the target.

These and other objects of the invention may be understood by reference to the following detailed description in conjunction with the accompanying drawing illustrating schematically an apparatus made in accordance with the invention.

The present invention is based upon the fact that if a target maintains its image in the vertical center of a directionally stabilized sight, the sight and the target must both have the same component of velocity in the same direction perpendicular to the line of sight. If the sight and the target also have a net component of velocity toward each other, the two will eventually collide.

According to the invention, the component of the air velocity of the aircraft perpendicular to the sight line is computed by multiplying the true air speed of thc craft by the sine of the included angle between the sight line and the direction of the aircraft heading. The component of the wind velocity perpendicular to the sight line is also computed by multiplying the wind speed by the sine of the included angle between the sight line and the wind direction. These two computed components are added algebraically to obtain the component of ground velocity of the aircraft perpendicular to the sight line, the output of this algebraic addition being a member which moves at a rate directly proportional to, and in a direction corresponding to, the aircrafts component of ground velocity perpendicular to the sight line.

If the components of aircraft ground velocity and target velocity perpendicular to the line of sight are equal and in the same direction, the target image will remain in the vertical center of the sight. However, if these components of aircraft ground Velocity and target velocity are unequal the apparatus can maintain the target in the vertical center of the sight by either of two methods, one of which in effect displaces the sight in a direction parallel to itself and perpendicular to the original sight line without changing the sight bearing, and by an amount equal to the displacement of the aircraft from the sight line, and the other of which rotates the sight in train through an angle whose sine is a function of the aircraits displacement from the sight line. It will be understood that sight line is intended to denote the line of sight, parallel to the original sight line, and passing through the target. Thus, the sight line may be moving or stationary, depending upon whether the target has a velocity component perpendicular to the sight line.

It will be apparent that it is impracticable to employ the first method to maintain the target image in the vertical center of the sight, in view of the limited amount by which the sight may be displaced on the aircraft without changing the sight bearing. Accordingly, the second method outlined above is utilized in the preferred practice of the invention. To this end, the computer element which moves at a rate directly proportional to the aircraft component of ground velocity perpendicular to the sight line is associated with an adjustable correction device which subtracts from this rate a rate proportional to the target velocity component in the same direction perpendicular to the sight line, so that if these two components are algebraically equal the output of the correction device is zero. A displacement indicator is operatively connected to the output end of the correction device, so that change of the displacement indicator is zero when the aircraft and the target have equal components of ground velocity in the same direction perpendicular to the sight line. If these two components are unequal, the output of the correction device corresponds in direction and is proportional in rate to the direction and rate, respectively, of the displacement of the aircraft from the sight line, that is, from a sight line tothe target and parallel to the original sight line. The displacement indicator actually multiplies the output rate of the correction device by time so that the reading of the indicator can be calibrated directly in miles or other unit of displacement perpendicular to the sight line. l

The displacement of the aircraft from the sight line and the range from the aircraft to the target are the two functions which determine the angle through which the sight should be rotated in train on its stabilized bearing so that the target image will remain in the vertical center of the sight even though the aircraft is displaced from the sight line. Thus, regardless of any maneuvers or change in the air speed of the aircraft, the target image Will remain in the vertical center of the stabilized sight as long as the target does not change its speed or heading. If the target maneuvers, its image will begin to creep from the vertical center of the sight, and thus the amount of correction (in terms of velocity) which must be subtracted by the adjustable correction device from the component of aircraft ground velocity perpendicular to the sight line must be either increased or decreased, depending upon whether the target has increased or decreased its velocity perpendicular to the sight line. This in effect controls the velocity of the sight line so that it alwayspasses through the center of the target and thus must travel with the same component of velocity perpendicular to the sight line. Accordingly, whenever the target image remains in the center of the sight, the velocity of the above correction factor is proportional to the component of velocity of the target perpendicular to the sight line.

If the torpedo is released on the sight line, as dened above, with its component of velocity perpendicular to the sight line equal to and in the same direction as the target velocity component perpendicular to the sight line, and with the torpedo headed in the general direction of the target, the two will collide. In accordance with the invention, the torpedo heading or bearing necessary to effect this collision is computed, in effect, by rotating a vector equal in length to the torpedo speed until its velocity component perpendicular to the sight line is equal to the target velocity component perpendicular to the sight line, and with the torpedo headed in the general direction of the target, the nal position of the vector representing the necessary torpedo bearing.

The torpedo must hit the water on the sight line, as defined above, in order that its component of velocity perpendicular to the sight line will be equal to the target component of velocity perpendicular to the sight line. When the aircraft is approaching the sight line at the instant of torpedo release, the release must be effected before the aircraft reaches the sight line, if the torpedo is to enter the water on the sight line. It will be apparent that this necessary lead will be a function of the aircrafts altitude and its rate of approach to the sight line at the instant of release. According to the present invention, after the necessary torpedo bearing is computed as described above, the aircraft is maneuvered to cause it to approach the sight line, and the rate of this approach is determined by measuring the rate of approach of the displacement indicator toward zero. The altitude of the aircraft above the water, being a direct function of time, can be converted into the time of fall of the torpedo from that altitude. This time factor is multiplied by the rate of approach of the aircraft toward zero displacement, as computed from the displacement indicator, so that the result is the displacement of the aircraft from the sight line at which the torpedo should be released to cause it to enter the Water on the sight line. By subtracting from the reading of the displacement indicator the value representing the product of the above multiplication, the torpedo when released at 'zero displacement (as represented by the modified indicator reading) will hit the water just as it crosses the sight line.

Referring now to the drawing, numeral 8 designates a standard compass repeater unit which is energized by the usual gyro iluxgate compass (not shown) on thel aircraft. The compass repeater 3 provides in effect a xed magnetic reference bearing, so that the output end of the-re- `peater 8 moves in accordance with changes in the heading of the aircraft. The output end of the compass repeater 8 is connected through gearing and shaft I6 to one side of a differential II. The output shaft Ila of the diiferential is connected to one side of a differential I2 having its output end connected through a shaft I3 and bevel gearing i4 to an optical sight I5. The shaft I3, gearing I4 and sight I5 are supported on a suitable mount (not shown) which is stabilized in roll and pitch. The sight I5 may be of any standard type and has the usual vertical hair line at the center of the sight, the sight being movable in train on its stabilized mount.

The sight I5 may be trained on the target by a sight bearing knob I6 connected through a shaft Ita to a gear I6b forming one of the input sides of a differential I1. The gear Iby operates through a shaft I8 and gearing IBa. to drive the other input side of differential II, that is, the side of the differential Ii opposite that which is driven from the compass repeater unit 8. Thus, the sight adjustment knob I6 serves to adjust the sight I5 in train relative to the directionally stabilized reference provided by the compass repeater unit 8, whereby any changes in the heading of the aircraft are compensated by the compass unit 8 through differential Ii to maintain the sight i5 on the sight bearing to which it was adjusted by knob I6. In other words, the sight 5 is directionally stabilized by the compass ren peater 8.

The output shaft IIa of differential II is also connected through friction gearing 2i! to a sine mechanism comprising a friction disk 2i driven by the gearing and having near its periphery a pin 2id. engaged in an elongated slot in a T-head 22. The stem 22a of the T-head is in line with the axis of rotation of the sine friction disk 2| and is suitably guided against lateral displacement. At its lower end, the stem 22a carries a cage 23 containing a pair of balls 24 disposed between a disc and a roller 26. The disc 25 is driven by a shaft 25a rotated at a speed proportional to the true air speed of the aircraft, as by means of a standard Pioneer air mileage unit (not shown). The latter is actually used as a source of power and drives the disc 25 at a speed proportional of the true air speed of the aircraft. This disc 25 and roller 26 are separated by a. distance equal to the sum of the diameters of the two balls 24, which are equal in diameter, and are spring loaded against each other through the balls 24.

The disc, balls and roller 25, 24 and 26 form a variable speed transmission or integrator. When the disc 25 is driven and the balls 24 are not at the center of the disc, the ball loaded against the disc will rotate and transmit the rotation through the second ball to the roller 26. Up to a certain limit, the magnitude of the spring loading will determine the tractive effort which the unit will transmit. The translation of the balls 24 by the stem 22a is restricted to a path parallel to the axis of roller 26. which is of a length equal to the diameter of the disc. Two balls 24 are used so that this translation can take place without skidding the balls on the disc or roller. If the balls 24 are positioned at the center of disc 25 by the sine mechanism, no rotation will be transmitted to the roller, but if the balls are positioned at the edge of disc 25 the roller will be driven at the maximum possible speed for the unit. The maximum speed is determined by the speed of rotation of the disc 25 and by the ratio of diameters of the disc and the roller. Intermediate speeds of rotation of the roller 26 are obtained in direct proportion to the displacement of the balls 24 from the center of the disc.

It will be understood that the sine disk 2l will be rotated by differential II through an angle representing the included angle between the sight bearing, as determined by adjustment of knob I6, and the heading of the aircraft, as determined by the compass repeater 6. Thus, when the axis of sight I5 is parallel to the longitudinal axis of the aircraft (heading), the sine disk 2l will be in the zero position shown,vwith the pin 21a. in line with stem 22a. However, when the heading of the aircraft is offset from the sight line, the sine disk 2| will be rotated through an angle equal to the angle of this offset, so that the balls 24 are displaced from the center of disc 25 through a distance proportional to the sine of this offset angle. The differential II drives the sine disk 2! with a one to one ratio with heading (compass repeater 3) and sight bearing (knob I6).

The angular velocity of roller 26 is equal to the product of the angular velocity of integrator disc y25 times the displacement of integrator balls 24.

Thus, the angular velocity of roller 26 is directly proportional to the product of air speed times the sine of the included angle between the bearing of sight i5 and the heading of the aircraft; that is, the output of roller 26 is an angular velocity proportional to the component of air speed peru pendicular to the sight line.

The component of the wind velocity perpendicular to the sight line is equal to the product of the wind speed times the sine of the included angle between the sight bearing and the wind direction. The wind speed is obtained from a variable speed transmission which receives its power from a constant speed driving disc 28. The variable speed transmission also includes a roller 29 and balls 39 mounted in a cage 3i, the transmission being similar to the transmission 24, 25 and 26 previously described. A wind speed knob 32 is operable through a pinion 33 and rack 34 to adjust a shaft 35 connected to the cage 3i. r)Che knob 32 is calibrated directly in terms of wind speed so that the displacement of the balls 36 from the center of disc 28 is directly propor tional to the wind speed. Thus, the roller 29 is driven at an angular speed directly proportional to the wind speed. The roller 29 is connected through bevel gearing 36 to a disc 31 forming part of another integrator or variable speed transmission to be referred to in greater detail presently.

A wind direction knob 46 is connected through a gear di to the other side of differential Il, that is, the side opposite the sight bearing gear leb. The output end of differential VI is connected through friction gearing 42 to a sine disk d3 having a pin 43a disposed in an elongated slot in a T-head 44, the stem t5 of the T-head being guided against lateral displacement. The T-head 44, sine disk 43 and pin 43a form a sine mechanism similar to that previously described. The stem 45 is connected to a cage 46 containing a pair of integrator balls 41 engaged between disc 3l and a roller 48. Since the wind direction and sight bearing are passed through differential Il' in opposite directions from knobs stil and it, respectively, the output of differential II is equal to the difference of the two, which is the included angle between the sight bearing and the wind direction. Accordingly, the sine mechanism 43 displaces the integrator balls 41 from the center of disc 31 through an amount directly proportional to the sine of the included angle between the sight bearing and the wind direction. The output of the integrator 31, 41 and 48 is equal to the product of the rotational speed of disc 31 times the displacement of balls 41 from the center of the disc, which is equal to the product of the wind speed times the sine of the included angle between the sight bearing and the Wind direction. Thus, the roller 48 rotates at a speed proportional to the component of the wind velocity perpendicular to the sight line and in a direction dependent upon the direction of this component relative to the sight line.

The component of ground speed of the aircraft perpendicular to the line of sight is obtained by algebraically adding the components of air ve-' locity and wind velocity previously obtained as described above, The two rollers 26 and 48 rotate with angular velocities proportional to the components of aircraft air velocity and wind velocity, respectively, perpendicular to the sight line. These rollers 26 and 43 are connected to opposite sides of a differential 50 so that the two angular velocities are passed through the differential with such directions of rotation that the output of differential 50 is equal to the algebraic sum of the two components. Accordingly, the output shaft of differential 50 rotates at a speed proportional to, and in a direction corresponding to, the component of aircraft ground speed perpendicular to the sight line.

A torpedo bearing indicator 52 is provided to indicate the true bearing on which the torpedo should be launched to effect a collision with the target. This bearing is obtained, in effect, by rotating a vector whose length is proportional to the torpedo speed, until the component of torpedo velocity perpendicular to the sight line is equal to and in the same direction as the target component of velocity perpendicular to the sight line. The component of torpedo speed is used to rotate the sight i 5 at such a rate that 'the target image remains in the center of the sight. At this time, the components of torpedo speed and target speed perpendicular to the sight line are equal. The component of the torpedo speed perpendicular to the sight line is determined by multiplying the torpedo speed by the sine of the torpedo angle, which is the included angle between the sight bearing and the torpedo bearing.

The torpedo speed is set into the computor by driving an integrator disc 54 at an angular velocity proportional to the known torpedo speed. The torpedo angle is set in manually by a knob 55 which operates through bevel gear 55a to rotate a sine gear 56 through the same angle. The sine gear 56 forms part of a sine mechanism 55a, 51 and 58 similor to the sine mechanism 2l, 2id and 22 previously described. The stem 5S of the sine mechanism is connected to a cage 59 containing integrator balls Si! engaged between the disc 54 and a roller SI. Rotation of the sine mechanism 58 thus displaces the integrator balls 60 from the center of disc 513 through an amount directly proportional to the sine of the torpedo angle as set in by knob 55. The output of the integrator or variable speed transmission 54, $0, 6I is equal to the product of the torpedo speed times the sine of the torpedo angle. Accordingly, the roller 6I has an angular speed proportional to the component of the torpedo velocity perpendicular to the sight line. If the targets image remains stationary in the sight I5, the output of roller 6| is also proportional to the component of the target velocity perpendicular to the sight line. Under this condition, the angle of rotation of sine mechanism 56 is equal to the torpedo angle.

The angular displacement (torpedo angle) of eine mechanism 56 is passed through a gear train B3, 64 to one side of a differential 65, the other side of the differential being connected through a gear t6 to the shaft ita operated by the sight bearing knob It. The output end of differential 65 is connected to the torpedo bearing indicator 52. It will be apparent that the sight bearing fed by knob it into the differential t5 is displaced by knob 55 through gearing 63, 54 by an angle equal to the torpedo angle, so that the output from differential 65, as shown on indicator 52, is equal to the torpedo bearing.

The components of the aircraft ground velocity and target ground velocity perpendicular to the sight line are subtracted in order to obtain the ground velocity of the aircraft relative to the target in a direction perpendicular to the sight line, that is, to obtain the aircrafts component of ground velocity perpendicular to a sight line to the target and parallel to the original sight line established by adjustment of knob iii. rthe output of differential 59, which is an angular velocity proportional to the aircrafts component of ground velocity perpendicular to the sight line, and the output of roller 6I, which is an angular velocity proportional to the targets component of velocity perpendicular to the sight line, are the two inputs to a differential 68. The output of differential @il is therefore an angular velocity directly proportional in magnitude, and corresponding in direction, to the aircraft component of velocity perpendicular to the moving sight line to the target, which is the rate of displacement of the aircraft from the moving sight line to the target. (lt will be understood that moving sight line is intended to denote a sight line to the target and parallel to the original sight line established by sight I5. Thus, the moving sight line may be moving or stationary depending upon whether the target has a velocity component perpendicular to the sight line.) If the angular velocity of the output of differential 58 is proportional to this rate of displacement of the aircraft from the moving sight line, the total number of revolutions of the output end of differential t8 is proportional to the total displacement of the aircraft from the moving sight line.

The output end of differential S8 is connected through a' shaft 69, worm 1U and worm wheel 1i to a displacement indicator 12. The displacement indicator is in effect a revolution counter calibrated in miles or other unit of clisplacement. It comprises a pointer 'i3 which rotates with the shaft 1l a on which wheel 'H is mounted. The pointer 13 cooperates with a scale 'lli in the form of a sector plate loosely mounted on shaft lla, the plate being suitably calibrated in terms of displacement to the right or left of a zero position (moving sight line). On its pe riphery the plate 14 has teeth l5 which mesh with a worm i6 mounted on a shaft 1i, for a purpose to be described presently. The worm and wheel i8, 'il provide a large gear reduction so that a large number of revolutions of output shaft 69 is required to move the pointer 13 through a relatively small angle.

The output shaft S9 of differential 68 also operates through bevel gears to drive a lead screw 8l which is threaded through a cage 82 containing the balls 83 of an integrator 84, 35

similar to the integrator previously described. The input to the integrator disc B4 is obtained from a constant speed motor drive. By reason of the lead screw 3|, the integrator balls 83 are displaced from the center of disc 84 through an amount directly proportional to theA aircrafts displacement from the moving sight line, as determined by the output of diierential 8B. Thus, the angular velocity of roller 85 is directly proportional to the displacement of the aircraft from the moving sight line.

An integrator disc 3l, driven at constant speed, engages one of a pair of integrator balls tu in a cage 9|). The other ball 8e engages a roller 9|, the disc, balls and roller 8l, 89, Si forming a variable speed transmission similar to those previously described. The cage Sil is connected to a rack 92 movable by a pinion es which may be rotated by a range knob S4. Thus, the integrator balls 89 are displaced from the center of disc 8l by an amount proportional to the range to the target, as set in by knob S4. rThe output roller 9| rotates at a speed proportional to a constant times the range and is connected through bevel gearing 9E to an integrator disc 91 which, therefore, also rotates at a speed directly pro portional to the range. The disc Sl forms part of a similar variable speed transmission 93, 99 and H3G, the cage 9,9 being connected to a stem ll of a sine mechanism |32, m2o, and |il3 similal` to the sine mechanism previously described.

`The integrator balls @il are thus displaced from the center of disc Sl b-y an amount proportional to the sine of the angle of rotation of sine fric` tion disk |02.

The integrator roller Ill assumes an angular velocity proportional to the product of the range times the sine of the angle of rotation of the sine disk |52. The outputs of the two rollers 85 and are geared to the two input sides, respectively, of a differential lil, the roller S being connected to differential it through gearing |38, and the roller lee being connected to the differential through a bevel gear |01. rIhe output or differential |95 is connected through a friction disk train HIE to the sin-e disk |il2. The output rate of roller 85 is proportional to the airplanes total displacement from the moving sight line, and the differential |05 subtracts the output from the two rollers 85 and ltd so that if the two are equal the diierential will have no output. If the two are unequal, the output of differential |85 drives the sine mechanism |62 which displaces the integrator balls S8 to a point where the roller Hl has the same angular velocity as roller lili, which is proportional to the displacement of the airplane from the moving sight line. The angular velocity of roller It!! is equal to the product of the angular velocity of the integrator disc Sil times the displacement of the balls 98, or the angular displacement rate of roller |06 is proportional to the range times the sine of the angle of rotation of sine mechanism |32. This can be expressed in the equation Displacement of airplane from moving sight line sine 0= Range and 0 is the angle through which the sight l5 must be offset so that the target will remain in the center of the sight even though the airplane is not on the moving sight line. The angle 0 is the angle of rotation of the sine mechanism m2, and that rotation is transmitted through a gear 10 train It to the other input side of differential i2 where it is combined with the sight bearing from differential Il. The output of diiierential |2 is the algebraic sum of the two inputs, and this output, as previously described, controls the magnetic bearing which the sight i5 assumes.

As pointed out in greater detail hereinafter, the torpedo is released to cause it to enter the Water on the moving sight line, that is, on Zero displacement as indicated by indicator l2. rIhe instant of torpedo release necessary to accomplish this is a function of the product or" the altitude of the aircraft times the rate of approach of the aircraft to the moving sight line. The output 69 ci differential 68 has an angular velocity directly proportional to the rate of the airplane displacement from or approach to the moving sight line. An integrator unit converts the angular velocity of shaft St to an angular displacement directly proportional to the rate of the airplane displace ment from or approach to the moving sight line. More particularly, the integrator unit comprises a constant speed disk H2 engaging one of a pair of integrator balls H3 mounted in a cage lill on a screw spindle H5, the other ball H3 engaging a roller It. The roller |6 is connected through gearing lll to one side of a diiferential llt, the other side of which is driven :from a gear SS on shaft t9. At its output end, the differential lit is connected to the screw spindle l I5 which, when rotated, adjusts the position of integrator balls l l 3 on disk i i2. It will be apparent that the angular velocity of shaft S9 and the angular velocity of output roller H5 are subtracted in the diilerential |13 so that the output of this diiierental is equal to the dierence of the ytwo values and controls the position of integrator balls llt. Since the integrator disk H2 is driven at constant speed, the output of integrator H2, i3 and llt is directly proportional to the displacement of the balls H3. If the two inputs oi" differential It are unequal, the output of differential ifi will displace the balls i i3 in such a direction and by such an amount that the output rate of roller i l5 will approach equality with the rate of rotation of shaft 59, that is, the rate of the aircraft dis-- placement from or approach to the moving sight line, Thus, whenever the system is in equilibrium, the linear displacement of the balls H3 will be directly proportional to the rate of displacement or approach of the airplane relative to the moving sight line, and also the output of differential llt will have turned through a pro portional number of revolutions in the process of displacing the balls H3. The rate of displacement is expressed in units of displacement per second, and the altitude can be expressed in the time of fall of the torpedo in seconds. Thus, when the two are multiplied the following equation results:

W X time displacement time This displacement will be in the same units that are calibrated on the displacement indicator 172. The linear displacement of the integrator balls H3 is multiplied by the time of fall of the toru pedo by passing the angular displacement of the output of differential H8 through a gear train l2@ whose ratio is proportional to the time of torpedo fall. It will be understood that the gear train 22d may be adjusted to provide a speed ratio corresponding to the predetermined altitude from which the torpedo is to be launched, that is, the predetermined time of fall of the torpedo. ylhe ll gear train drives the shaft l1 which operates through worm '16 and teeth J5 to offset the dial l'Ll and move the zero position thereof a slight amount. When the torpedo is dropped from the aircraft at Zero displacement, as represented on indicator I2, the torpedo will enter the water directly under the airplane at the instant that the airplane crosses the moving sight line, regardless of the altitude of the aircraft or the rate of its approach to the sight line.

In the operation of the torpedo director, the torpedo speed is set in when the torpedo is loaded into the plane, by adjusting the speed of disk Eli. The altitude of torpedo drop is assumed by the pilot before the run, and the ratio of gear train 12D is adjusted to correspond to the time of fall from the desired altitude. If desired, however, the altitude can be set in continuously by employing a variable speed transmission between spindle i I5 and shaft il and adjusting the transmission from a suitable altimeter. The wind velocity is set in to the unit manually by knob 32 calibrated in knots or other unit of velocity, and can be determined from the home base or by drift sight or approximation. The wind direction is set in manually by knob iii having a dial (not shown) similar to a compass dial. The wind direction can be obtained from the home base or by drift sight or approximation. lThe range is set in by the range knob Sil. This setting may be made on the basis of an estimated range, because the range has very little effect on the accuracy of the computer, since the torpedo is always rel-eased on the moving sight line where the angle of offset of which range is a function is zero.

When the aircraft is in night and a target is sighted, the sight bearing knob I6 is adjusted to train the sight l5 on the target, so that the vertical hair line of the sight intersects the target. At the same time, the system is started in operation, with the displacement indicator '2 at zero, by starting the constant speed driving members 252, 54, at, 81, and H2 and connecting the in tegrator disk to the air mileage unit through i a shaft 25a. If the target image in the sight l5 commences to creep to the right or left of the vertical hair line, the torpedo angle knob 55 is adjusted to cause the image to move back to the hair line and to be maintained on the hair line.

As pointed out heretofore, when the target image remains on the vertical hair line 0f sight l5, the correction roller El is rotating at a rate proportional to the target Velocity component perpendicular to the original sight line. this condition is obtained, the torpedo bearing indicated on the indicator 52 is the true bearing on which the torpedo is to be released to effect a collision with the target. During the attacking run of the aircraft, dicator 12 continuously indicates the total displacement of the aircraft from the moving sight line, the rate of movement of pointer 13 indicating the rate of aircraft displacement from the moving sight line. stabilized by adjustment of the torpedo angle knob so that the target image remains in the `Avertical center of the sight, the airplane 1s maneuvered so as to cause displacement pointer i3 to move back toward the zero position on dial M. When the pointer 13 reaches the zero position, the torpedo is released manually or automatically to cause it to enter the water at the moving sight line and on the torpedo bearing shown on indicator 52. It will be understood When the displacement in- When the system has been that with ordinary torpedoes the aircraft must assume the torpedo bearing shown on indicator 52 before releasing the torpedo, but if a maneuverable torpedo is used the torpedo bearing can be stabilized in the torpedo so that the aircraft can assume any heading when the torpedo is released.

The new method and apparatus permit considerable maneuvering of the attacking craft during solution of the fire control problem and prior to release of the torpedo, so that the attacking craft is less vulnerable to defensive action. The method may be practiced with ease by the use of the new apparatus, and the invention provides an accurate solution of the torpedo bearing and dropping point to effect a hit on the target. It will be apparent that the apparatus may be readily adjusted to compensate for evasive maneuvers of the target prior to release of the torpedo, by manipulation of torpedo angle knob 55 to maintain the target image on the vertical center of the sight I5.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In an apparatus for use on a moving craft to direct a torpedo from the craft to a moving target the combination comprising a directionally stabilized member, a rst differential having a manually settable input to set said member to a position parallel with an original line of sight from the craft to the target, computing means for moving the said member in train through an angle 0, said computing means including a rst element rotatable at a rate proportional to the velocity component of the Craft perpendicular to the original sight line, a second element rotatable at a rate proportional to the predetermined torpedo velocity, a third rotatable element, a speed varying member coupling said third element to said second element, angularly rotatable means for manually adjusting said speed varying member so that the rate of rotation of the third element is proportional to the torpedo velocity multiplied by the sine of the angle of rotation of said manually adjustable means, a fourth rotatable element, a source of constant speed, speed varying means for transmitting rotation from said source to said fourth element at a rate proportional to a displacement D corresponding to the integrated difference in rate of rotation of said first and third elements, means rotatable at a rate proportional to the range R from said craft to said target, a second differential means having as output feeding said rst differential for positioning said directionally stabilized member in train through said angle 0 determined by the difference in inputs to said res estive differentials, a fifth rotatable element, me ns adjustable by the output of said diff-erential means to drive said fth element at a rate proportional to said range multiplied by the sine of the angle 6, said inputs to said differential means comprising said fourth and fifth rotatable elements whereby said differential output will be zero whose 0 equals an angle whose Sine is said range divided by said displacement, means positionable to an angle corresponding to the dinerence in manual setting of said member and said angularly rotatable means whereby to indicate the correct bearing angle at which said torpedo is to be released at zero displacement when said 13 angularly rotatable means is manually adjusted an amount to keep said member parallel to azimuth bearing line to said target.

2. The combination dened in claim 1 above characterized further by the addition thereto of an indicator for said displacement D having a pointer movable at a rate proportional to the diierence in rate of said rst and third elements whereby said pointer will be movable to a position Corresponding to the integrated difference in rate of said first and third elements, a scale for said pointer and means for moving said scale in a direction opposite to the movement of said pointer at a rate proportional to said displacement multiplied by tne time of fall of said torpedo froma predetermined altitude of said craft whereby upon release of said torpedo from said craft at a displacement Dz() as indicated by said pointer on said dial, the torpedo will enter the Water on the sight line having a bearing to said target such that the component of velocity of said torpedo normal to the sight line Will equal the component of velocity of said target normal to said sight line.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,105,147 Inglis Jan. 11, 1938 2,161,081 Ovtschinnikoff June 6, 1939 2,194,141 Estoppey Mar. 19, 1940 2,402,088 Ross June 11, 1946 2,412,585 Klemperer et al. Dec. 17, 1946 2,413,846 Ross Jan. 7, 1947 2,428,372 Knowles et al Oct. 7, 1947 

